What are the indications for an obturator nerve block?

Indications for Obturator Nerve Block

The primary indications for obturator nerve block include prevention of thigh adductor jerk during transurethral resection of bladder tumors, postoperative analgesia for knee surgery, treatment of hip pain, and management of persistent hip adductor spasticity. 1

Primary Indications

• Prevention of obturator reflex during urological procedures: Obturator nerve block is indicated to prevent the thigh adductor jerk reflex during transurethral resection of bladder tumors, which can reduce surgical complications 1

• Postoperative pain management: Obturator nerve block is used as part of multimodal analgesia for knee surgery and can reduce the requirements for postoperative analgesia 2, 1

• Treatment of hip pain: Both acute and chronic hip pain can be managed with obturator nerve block, with some patients experiencing pain relief lasting weeks to months after a single injection 3

• Management of adductor muscle spasticity: Neurolytic blockade of the obturator nerve is effective for treating intractable spasticity of adductor thigh muscles in patients with neurological conditions such as hemiplegia or paraplegia 4

Surgical Considerations

• Proximal femoral fracture surgery: Obturator nerve block may be used as part of peripheral nerve blockade (along with femoral and lateral femoral cutaneous nerve blocks) for analgesia during and after proximal femoral fracture surgery 2, 5

• Hip arthroplasty: The block can be used as part of multimodal analgesia for hip replacement procedures, though newer techniques like PENG (Pericapsular Nerve Group) block may be preferred in some cases 6

Diagnostic Applications

• Diagnostic tool for hip pathology: CT-guided obturator nerve block can be used diagnostically to determine if hip pain originates from structures innervated by the obturator nerve 3

Technical Considerations

• Approach selection: Different approaches (proximal vs. distal) should be considered based on the specific indication:

  • The proximal approach may be superior for reducing local anesthetic dose and providing successful blockade of all branches, including the hip articular branch 1
  • The distal approach at the inguinal crease requires two separate injections for the anterior and posterior branches 1

• Guidance techniques: Ultrasound guidance has improved the accuracy and safety of obturator nerve blocks, with CT guidance also being effective for precise localization 1, 3, 7

Important Caveats

• Assessment of block success: Evaluation of adductor muscle strength is the most reliable method to confirm successful obturator nerve block, as cutaneous sensory changes are inconsistent or absent in many patients 8

• Anatomical variability: The obturator nerve typically divides into anterior and posterior branches before the site of injection, requiring consideration of both branches for complete blockade 8

• Risk considerations: In patients on anticoagulants, the risk of deep hematoma formation should be carefully evaluated before performing the block 9

• Potential complications: While generally safe, practitioners should be aware of the proximity to vascular structures and use imaging guidance to minimize risks 7